<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        //关键字
        //变量名称
        //用等号给变量赋值
        //等号右边是值，值可以为任何类型

        //变量名的特殊点
        //驼峰命名

        var userName = 123;

        console.log(userName);

        var width = 100,height = 200;// -->不推荐
        console.log(width);
        console.log(height);
    </script>
</body>
</html>